It was hypothesised that Nannochloropsis limnetica due to the
specific chemical composition and fatty acids profile, may positively affect rumen
fermentation. To confirm this hypothesis the batch culture experiment
was conducted to evaluate N. limnetica supplemented at 0, 2, 4 and 6% of
the substrate dry matter (DM) on both fermentation and fatty acid proportion
in the ruminal culture. It was found that microalgae N. limnetica contain
(g · kg−1 DM): crude protein 238, Ca 48.7, Na 31.8 and unsaturated fatty acids
(51.7 g · 100 g−1 fatty acids). Moreover, leucine and lysine were the most abundant
essential amino acids in the analysed microalgae. The total bacteria count
was negatively affected if N. limnetica algae were supplemented at more than
4%. So, the research hypothesis that microalgae N. limnetica may affect rumen
fermentation was confirmed, mainly by increasing propionic acid concentration
without changes in the total volatile fatty acids concentration. However,
a high dose (6%) decreased rumen bacteria count. Further research under
commercial farm conditions should be conducted to confirm the usefulness of
freshwater microalgae N. limnetica as a feed additive for ruminants.

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